Memory and thinking problems are the most common symptoms associated with a dementia diagnosis. However, non-cognitive symptoms may appear years or even decades earlier.
Alzheimer’s disease, which accounts for 60 to 80 percent of dementia cases, can progress through three main stages. The first stage can begin between 15 and 20 years before obvious cognitive changes appear. During this time, the brain begins to shrink and misfolded proteins, hallmarks of Alzheimer’s, begin to build up: sticky beta-amyloid plaques in the brain and tau tangles in neurons.
This is followed by mild cognitive impairment, in which people begin to have notable memory and cognition problems but otherwise maintain good overall functioning. Next comes the “dementia” stage, when multiple cognitive domains are affected, leading to the inability to function independently in daily life.
Scientists believe that the biological changes that occur in the brain during the first and second stages can cause emotional, sensory and physical symptoms even years before a possible diagnosis.
“You can have many of these other precursors, but not have any cognitive symptoms,” said Timothy Chang, an associate professor of neurology at UCLA.
Of course, experts caution that having early symptoms linked to an increased risk of Alzheimer’s doesn’t mean you will necessarily develop dementia, and that about 45 percent of dementia cases can be prevented with lifestyle changes.
Here are six early symptoms that often appear in people who are later diagnosed with Alzheimer’s disease.
Depression and anxiety that begin later in life
Depression is a known risk factor for dementia. A 2023 study of more than 1.4 million Danish adults found that the risk of dementia was 2.4 times higher in those diagnosed with depression.
But depression and anxiety that develop later in life, around age 55 or 60, can also be warning signs that something is wrong.
“The idea is that some of the neural network changes that occur in the early stages of dementia also affect mental health,” so changes in mental health are “a sign of possible early changes in brain function,” Chang said.
Researchers have found that having these mood symptoms can also speed up the progression of dementia.
Increased apathy, irritability, or agitation.
Neuropsychiatric symptoms, such as irritability and agitation, are common in Alzheimer’s disease and can be detected before cognitive decline occurs.
A 2017 study of about 1,400 people found that about 31 percent of cognitively healthy older adults had mood-related symptoms, compared to about 47 percent among those at higher risk of dementia and about 54 percent in people with mild cognitive impairment.
According to Adam Turnbull, a professor of psychiatry and behavioral sciences at Stanford University, who wrote a recent paper on alterations in emotion regulation in preclinical Alzheimer’s disease, between 50 and 60 percent of people with biomarkers of Alzheimer’s pathology present at least one neuropsychiatric symptom.
“If you feel like you are angry and moody all the time, that you yell at people, and that your relationships with others seem to be marked by constant fighting and negative vibes, then seek mental health support” from a geriatric psychiatrist, Turnbull said.
Sleeping problems
According to Turnbull, since good sleep can be a protective factor, lack of sleep can serve as “an indicator that something is not right.”
According to a 2025 meta-analysis of 39 studies, sleep apnea and other sleep disorders, such as excessive daytime sleepiness, restless legs syndrome, and circadian rhythm disorders, are associated with an increased risk of dementia.
Insomnia or a lack of rest at night can also precede dementia. A study of more than 4,400 cognitively healthy older adults found that sleeping less at night or sleeping more during the day was linked to greater accumulation of beta-amyloid—a biological hallmark of Alzheimer’s disease—in the brain.
On the other hand, each additional hour of nightly sleep was associated with a decrease in beta-amyloid levels. Research suggests that getting a good night’s sleep can help clear brain waste, including beta-amyloid.
Of course, there’s no need to worry about an afternoon nap. But sleeping a lot during the day and then not sleeping well at night can be a cause for concern, Turnbull said.
Loss of sense of smell
Our sense of smell is linked to brain health, and loss of this sense is often one of the first signs of neurodegenerative disorders, such as Alzheimer’s disease and Parkinson’s disease. About 85% of people with early-stage Alzheimer’s have trouble smelling.
The nose has a unique connection to the brain. Compared to other senses, such as hearing and sight, olfactory information is sent more directly to the cerebral cortex, where it connects with areas important for cognition, memory, and mood, such as the hippocampus and amygdala.
Interestingly, the olfactory nerve has the ability to regenerate, and people can improve their sense of smell through training. There is even preliminary evidence that olfactory training can improve cognition, even in people with a normal sense of smell.
Walk slower
For years, changes like walking slower, taking shorter steps, or having a longer stride were considered a normal part of aging. But current research suggests that these changes may precede and predict cognitive decline and other neurological problems.
A study conducted in 2024 with more than 1,300 healthy adults over 65 years of age revealed that walking ability, including walking speed and the ability to turn 360 degrees, decreased up to a decade before cognitive decline.
Lower grip strength
Grip strength is closely related to healthy aging and may be a better indicator of life expectancy than blood pressure.
Lower grip strength is also associated with poorer cognitive health. A recent study that analyzed more than 190,000 adults found that each 5 kg decrease in grip strength was associated with a 20% increase in dementia in men and 12% in women. Likewise, lower grip strength was related to lower problem-solving scores and worse performance on a memory task.
Grip strength is one of the ways doctors assess physical frailty, along with gait. In medical terms, physical frailty means that the body is more vulnerable to illness and injury. It is both a risk factor for dementia and a possible early warning sign that can appear about a decade before cognitive symptoms begin.
When to talk to your doctor
“If you are an older adult and you notice these symptoms, don’t be alarmed or think it is dementia,” Turnbull said. “There’s a good chance it has nothing to do with a neurological problem.”
But if you are concerned about your memory or reasoning ability, especially if you have any of these symptoms, it is important to consult with your doctor. Recent advances in diagnostics, such as positron emission tomography (PET) scans, lumbar puncture and a new blood test, allow Alzheimer’s biomarkers to be detected earlier, which could speed up treatments.
“I think it’s good to do an evaluation and have a doctor give their opinion on whether something is concerning or not,” Chang said.
How to reduce the risk of dementia
There is a genetic component to the risk of dementia, but there are also many ways we can reduce this risk.
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Last year, the US POINTER clinical trial found that a combination of exercise, a healthy diet, social interaction and brain games could improve cognitive abilities in older adults at risk of cognitive decline or dementia.
Other studies have found that eliminating alcohol, getting regular vaccinations, and protecting our hearing could help preserve cognitive function.